The present invention relates, in general, to improvements in audio-visual display apparatus, and, more particularly, to audio-visual teaching and testing devices which coordinate the projection of individual picture transparencies with the reproduction of corresponding sound information from a recording.
The uses of audio-visual in entertainment, commercial, and educational fields are well recognized, and such devices are in great demand. Because recent developments have produced light-weight portable, easy-to-use machines, they have come into greater demand, particularly for use with the educationally disadvantaged and in developing countries. Such uses, however, place a premium on reliability, on the ability of a machine to handle a wide variety of functions for more effective teaching and testing of students, on ease of use, and on accuracy in the coordination of visual and audio information. If such machines are to respond to the wide variety of uses to which they may be placed, the machines must have capability for producing a wide variety of visual display and sequences not only in response to predetermined teaching patterns, but in response to the patterns of answers produced by the user of the machine during testing and learning procedures.
Although prior machines have been capable of producing extremely useful displays and accompanying narration, such devices have been limited in the patterns and responses they can provide, primarily because of limitations in the mechanical structure and the control circuitry of such machines. Although prior devices have been generally satisfactory, the increasing need for greater flexibility in establishing desired patterns and programs for instruction or testing, and the need to allow changes in existing patterns and procedures to permit machines to be updated to meet new techniques and theories and to accommodate newly developed programs is now recognized. It is to meet these needs that the present invention was developed.
Typical of prior art machines is that described and illustrated in U.S. Pat. No. 3,504,445 to Goldmark et al, issued April 7, 1970, the disclosure of which is hereby incorporated by reference. The present invention is directed to an improved version of the apparatus disclosed in that patent.